so far cut out a hole in them and sanded them smooth took abt 30 mins started at 2.55pm and looked at clock at 3.20pm to do four holes and sanded them and thinking of doing this putting couple on top of one another 2 or 3 or 4 high to save space in tank pics will show them not sealent together yet

nex step is to seal them together with fish safe clear aquarium sealant